It frequently contributes to the smogs over Los Angeles.

同时它也常常引起洛杉矶上空的烟雾。

First: "It's only nature, we've always had smogs, what's the big deal?"

第一：“那是自然的事情，我们一直有雾，有什么大不了的？”

Vehicles also cause air pollution, which produces city smogs, acid rain, and global warming.

交通工具也能造成空气污染，这种污染也产生了城市烟雾，酸雨和全球变暖。